In a wireless cellular communication system, for acquiring network services, a UE (User Equipment) needs to know related configuration information of a current service cell, and a cell reselection in a moving process of the UE also needs to acquire adjacent cells' configuration information, such as a channel bandwidth, a system frame number, a network ID, residing availability, a configuration relating to measurement. All this configuration information is called system information.
The system information is classified into essential system information and non-essential system information. The essential system information of a cell include fundamental information relevant to residing in and accessing to the cell. Usually, the essential system information system information has a relatively small volume and is broadcasted. The non-essential system information refers to system information other than the essential system information and may be sent to the UEs in a cell through dedicated channel. Under conditions, such as updating, re-configuring or call barring of a cell, the system information changes and all UEs in the cell should be informed to acquire the updated system information.
However, sending all the updated non-essential SI (System Information) to every UE in the cell through dedicated channel will cost too much radio resources while system information updating.